The first chiral phosphine-catalyzed activation of acrylates for intramolecular formal [2 + 4] reactions with unsaturated imines is described. The catalytic reactions afford N-heterocycles with exceptionally high diastereo- and enantioselectivities. The [2 + 4] products are amenable for further transformations to useful molecules such as chiral piperidines and multicyclic structures.

A diverse array of biologically active, lipid-soluble alkaloids have been discovered in amphibian skin. Such alkaloids include the following: the steroidal samandarines from salamanders, the batrachotoxins, histrionicotoxins, gephyrotoxins, and epibatidine from neotropical poison frogs (Dendrobatidae), the pumiliotoxins, allopumiliotoxins, homopumiliotoxins, and decahydroquinolines from certain...

The rates of reaction with nitrous acid of four methylsubstituted piperidines to form the corresponding Nnitrosopiperidines were compared with that of piperidine. The relative rates for piperidine, 2-methyl-, 2,6-dimethyl-, and 2,2,6,6-tetramethyl-piperidine were approximately 100:20:10:1, showing considerable steric hindrance tp nitrosation by the «methyl groups. The rate of formation of nitr...

2-(2-Cyano-2-phenylethyl)aziridines were converted into novel cis- and trans-2-chloromethyl-4-phenylpiperidine-4-carbonitriles via alkylation with 1-bromo-2-chloroethane followed by microwave-assisted 6-exo-tet cyclization and regiospecific ring opening. The latter piperidines were used as eligible substrates for the synthesis of stereodefined 2-chloromethyl-, 2-hydroxymethyl-, and 2-carboxymet...

A practical and highly stereoselective approach to access 2,6-disubstituted piperidines using an amidine auxiliary is reported. Following the diastereoselective addition of Grignard reagents at the 2-position of an activated pyridinium salt, the amidine group directs a regioselective metalation at the 6-position, enabling further functionalization. A subsequent electrophilic quench or a Negishi...

Dwoskin et al. (*) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 238 days.

in this paper functionalized multiwall carbon nanotubes (fmwcnt) were modified using doxycycline, containing reactable nitrogen, which can attach chemically to functionalized mwcnt. the synthesized nano compounds were characterized by fourier transform infrared spectroscopy (ft-ir) and raman spectroscopy. these spectrums proved the existence of nitrogen atoms of amide functional groups. the mor...